1. Field
The present invention relates to a test device for a display panel and a method of testing a display panel.
2. Description of Related Art
Currently, various flat panel displays that can reduce weight and volume, which are drawbacks of a cathode ray tube, are being developed. Flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), organic light emitting diode (OLED) displays, and the like.
OLED displays display images using OLEDs that generate light by a recombination of electrons and holes, have a fast response speed, are driven with low power consumption, and have excellent luminous efficiency, luminance, and viewing angle.
In general, OLED displays are classified into a passive matrix type OLED (PMOLED) and an active matrix type OLED (AMOLED), according to a method of driving OLEDs.
The PMOLED display uses orthogonal positive electrodes and negative electrodes and a driving method of selecting negative lines and positive lines. The AMOLED display uses a driving method of sustaining a data voltage by forming a thin film transistor and a capacitor in each pixel and storing the data voltage in the capacitor. The PMOLED display has a simple structure and is relatively inexpensive, but is generally difficult to manufacture a panel of large size or high precision. In contrast, the AMOLED display can include a panel having large size or high precision, but a method of controlling the AMOLED display is technically difficult to implement. Furthermore, an AMOLED display is relatively expensive to manufacture.
In consideration of resolution, contrast, and operation speed, an AMOLED display that selectively turns on each pixel is primarily used.
A pixel of the AMOLED display includes an OLED, a driving transistor that controls an amount of current that is supplied to the OLED, and a switching transistor that supplies a data signal, which controls light emitted from the OLED, to the driving transistor.
In regards to a driving transistor of the pixels of the AMOLED display, a difference occurs in current flowing to the OLEDs due to a variation of threshold voltages of the driving transistors or a variation of a power source voltage that is supplied to each pixel, and thus a variation occurs in luminance of the OLEDs.
For example, currently, as the size of the display panel of the OLED display increases, the power consumption increases, and it is difficult to manufacture a screen of high image quality and high precision that also emits light with uniform luminance.
To meet needs for improving quality of the display panel of the display device, research regarding a device and method for measuring, testing, diagnosing, and checking for improving image quality and power consumption of the display panel is ongoing.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.